G2427.10 (503.10) Vent Connectors for Category I Appliances
Where the vent connector used for an appliance having a draft hood or a Category I appliance is located in or passes through attics, crawl spaces or other unconditioned spaces, that portion of the vent connector shall be listed Type B, Type L or listed vent material having equivalent insulation properties.
Exception: Single-wall metal pipe located within the exterior walls of the building in areas having a local 99-percent winter design temperature of 5°F (-15°C) or higher shall be permitted to be used in unconditioned spaces other than attics and crawl spaces.
Where vent connectors for residential-type appliances are not installed in attics or other unconditioned spaces, connectors for listed appliances having draft hoods, appliances having draft hoods and equipped with listed conversion burners and Category I appliances shall be one of the following:
- Type B or L vent material.
- Galvanized sheet steel not less than 0.018 inch (0.46 mm) thick.
- Aluminum (1100 or 3003 alloy or equivalent) sheet not less than 0.027 inch (0.69 mm) thick.
- Stainless steel sheet not less than 0.012 inch (0.31 mm) thick.
- Smooth interior wall metal pipe having resistance to heat and corrosion equal to or greater than that of Item 2, 3 or 4.
- A listed vent connector.
Vent connectors shall not be covered with insulation.
Exception: Listed insulated vent connectors shall be installed in accordance with the manufacturer's instructions.
A vent connector for a nonresidential, low-heat appliance shall be a factory-built chimney section or steel pipe having resistance to heat and corrosion equivalent to that for the appropriate galvanized pipe as specified in Table G24188.8.131.52. Factory-built chimney sections shall be joined together in accordance with the chimney manufacturer's instructions.
As an alternative method applicable only where all of the appliances are draft hood equipped, each vent connector shall have an effective area not less than the area of the draft hood outlet of the appliance to which it is connected.
Where two or more appliances are vented through a common vent connector or vent manifold, the common vent connector or vent manifold shall be located at the highest level consistent with available headroom and the required clearance to combustible materials and shall be sized in accordance with Section G2428 or other approved engineering methods.
As an alternate method applicable only where there are two draft hood-equipped appliances, the effective area of the common vent connector or vent manifold and all junction fittings shall be not less than the area of the larger vent connector plus 50 percent of the area of the smaller flue collar outlet.
Exception: The clearance between a vent connector and combustible material shall be permitted to be reduced where the combustible material is protected as specified for vent connectors in Table G2409.2.
TABLE G2427.10.5 (503.10.5)
CLEARANCES FOR CONNECTORSa
|APPLIANCE||MINIMUM DISTANCE FROM COMBUSTIBLE MATERIAL|
|Listed Type B|
gas vent material
|Listed Type L|
|Listed appliances with draft hoods and appliances listed for|
use with Type B gas vents
|As listed||As listed||6 inches||As listed|
|Residential boilers and furnaces with listed gas conversion|
burner and with draft hood
|6 inches||6 inches||9 inches||As listed|
|Residential appliances listed for use with Type L vents||Not permitted||As listed||9 inches||As listed|
|Listed gas-fired toilets||Not permitted||As listed||As listed||As listed|
|Unlisted residential appliances with draft hood||Not permitted||6 inches||9 inches||As listed|
|Residential and low-heat appliances other than above||Not permitted||9 inches||18 inches||As listed|
|Medium-heat appliances||Not permitted||Not permitted||36 inches||As listed|